Post-mortem Energy Metabolism Research Articles

Feedback regulation between AMPK and HIF-1α contributes to color stability via energy metabolism and mitochondrial efficiency regulation of yak meat

Despite the well-established individual roles of AMP-activated protein kinase (AMPK) and hypoxia-inducible factor-1α (HIF-1α) in sensing energy stress and/or hypoxia in postmortem muscle, a knowledge gap persists regarding their interplay and the consequent impact on the yak meat color stability. This study aimed to elucidate the AMPK–HIF–1α interaction and its consequential impact on mitochondrial functionality, energy metabolism, and ultimately, color attributes. Postmortem yak longissimus thoracis et lumborum (LTL) muscles were incubated with saline, AMPK inhibitor (Compound C), Compound C plus HIF-1α activator (DMOG), and Compound C plus HIF-1α inhibitor (YC-1) for 0, 6, 12, 24, 72, and 120 h, respectively. Results indicate that Compound C hindered the nuclear translocation of HIF-1α (P < 0.001), in turn, DMOG upregulated AMPK protein levels (P < 0.05) by a yet unknown mechanism. Mass spectrometry analysis identified seven AMPK-induced phosphorylation sites (Ser58, Thr63, Ser65, Tyr66, Thr677, Ser14, and Ser15) mapped onto three phosphopeptides on HIF-1α. Moreover, Compound C induced a significant reduction in energy metabolism levels, evidenced by decreased glycogen degradation, lactate accumulation, and pH decline (P < 0.05). Besides, Compound C promoted a consistently decreased mitochondrial protein yield, reduced NADH content, and OCR (P < 0.05). However, DMOG attenuated the effects of Compound C on mitochondrial efficiency, and interconversion of oxy-to deoxymyoglobin. Collectively, these findings establish the collaborative influence of AMPK and HIF-1α on postmortem energy metabolism, concurrently emphasizing their antagonistic effects on mitochondrial function.

Muscle of dark and normal beef differs metabolically

Reduction in muscle glycogen triggered by adverse antemortem handling events alters postmortem energy metabolism and results in a high ultimate pH and dark, firm and dry beef, often referred to as ‘dark-cutting’. However, the relationship between atypical dark (AT) beef, postmortem energy metabolism and underlying tissue characteristics remains somewhat unclear. Cattle harvested in the US and Canada representing normal (pH < 5.6), AT dark (pH 5.6–5.8) and dark cutting (DC; pH > 5.8) beef were analyzed for tissue characteristics related to energy metabolism. Results show AT dark beef is more oxidative but similar to normal beef in glycolytic potential and nucleotide abundance. Mitochondria DNA content (P < 0.05, Canada; P < 0.005, US) and oxidative enzymes for DC and AT dark beef were greater (P < 0.01; Canada and US) compared to normal beef. Myoglobin tracked (P < 0.01) with color classification. These findings show both DC and AT beef are inherently more oxidative and raise the possibility that more oxidative muscle may be more prone to develop dark beef.

Effects of guanidinoacetic acid on the growth performance, meat quality, postmortem energy metabolism and muscle fibre types of finishing pigs

Context Meat quality is increasingly being paid more attention by customers and enterprises. However, the modern pursuit of pork production has led to a decline in pork quality. Muscle fibre type is one of the important factors affecting meat quality that can be used as a key control point. Aims This study set out to assess the effects of dietary guanidinoacetic acid (GAA) on the growth performance, meat quality, postmortem energy metabolism, and muscle fibre types of finishing pigs. Methods In total, 180 healthy Duroc × Landrace × Meishan cross castrated male pigs with the similar weight (average 90 kg) were randomly divided into three treatments, with five replicates (pens) per treatment and 12 pigs per pen, including a GAA-free basal diet and basal diet with 0.05% or 0.10% GAA for 15 days. Key results In longissimus thoracis muscle, the results indicated that GAA supplementation decreased the drip loss and the cooking loss in 0.10% GAA group. Meanwhile, in semitendinosus muscle, 0.10% GAA addition increased pH45 min, and decreased the cooking loss. Additionally, GAA addition increased the content of ATP and AMP in semitendinosus muscle. The mRNA expressions of MyHC-I and MyHC-IIa were increased, whereas MyHC-IIx and MyHC-IIb were decreased. Moreover, in longissimus thoracis muscle, GAA addition promoted the mRNA expressions of CaM and NFATc1; in semitendinosus muscle, dietary GAA up-regulated the CnA and NFATc1 mRNA expressions. Conclusions GAA addition improved the meat quality, enhanced postmortem energy metabolism and promoted the conversion of fast-muscle fibre to slow-muscle fibre via activating the CaN/NFAT signalling. Implications The addition of GAA can improve the meat quality of post-slaughter finishing pigs and provide a theoretical basis for the application of GAA in livestock production.

Ractopamine does not rescue Halothane and Rendement Napole metabolism postmortem

The objective of this study was to determine if ractopamine (RAC) impacts postmortem muscle metabolism and subsequent pork quality in Halothane (HAL) and Rendement Napole (RN) mutant pigs. All RAC fed pigs had increased (P < 0.04) L* values. HAL and RN mutants muscle had lower (P < 0.01) pH values but RAC feeding had no effect. RN mutants had higher and lower (P < 0.05) muscle pH and temperatures, respectfully at 15 min and RN mutant pigs had greater (P < 0.0001) glycogen initially but lactate levels similar to wild type (WT) pigs at 24 h. RAC lowered (P < 0.05) glycogen in RN mutants but not in HAL mutated or WT pig muscle. These data show RAC feeding changes postmortem energy metabolism but does not change pH and pork quality hallmark of two major pig gene mutations and supports our contention that ultimate meat quality traits and their biochemical drivers may be more complex than originally reasoned.

Proteomic analyses of mitochondrial damage in postmortem beef muscles.

The objective of the study was to examine the expression profiles of mitochondrial proteins in at-death and 24 hpostmortem (PM) using tandem mass tag (TMT) approach to characterize the mitochondria possible mechanisms that are affiliated with tenderization. Results showed that the tender meat at 24 hPM emerged with more serious mitochondrial damage. Altogether 456 mitochondrial proteins were identified, including 442 down-regulated and 14 up-regulated proteins. These differentially-expressed proteins were primarily involved in the progress of PM energy metabolism, apoptosis, and the morphological alterations of mitochondrial. Among them, 47 subunits (such as NDUFA2, COX4I1, and ATP5PB) were annotated into the oxidative phosphorylation pathway. VDAC1, VDAC2, and VDAC3 involving in the damage of MPTP, and IMMT, CHCHD3, APOL and APOO modulating the morphology of mitochondria, and DIABLO and AIFM1 released from mitochondria affect caspase's activation. HSPD1 and HSPE1 involved in apoptosis, mitochondrial physiological and morphological alterations. The earlier-mentioned proteins were validated as potential indicators of tenderness regulated by mitochondrial damage. These results highlighted that mitochondrial damage possibly participate in PM tenderization of beef muscles by energy metabolism and cell apoptosis status. © 2022 Society of Chemical Industry.

Mitochondrial activity as an indicator of scallop (Mizuhopecten yessoensis) adductor muscle in early cold storage.

The purpose of this study was to reveal the role of mitochondria in indicating a change in the freshness of the adductor muscle of Mizuhopecten yessoensis during cold storage and hardening. The adductor muscle hardens after 96h of cold storage and reaches the maximum degree of hardening in 6h. In this study, after hardening (102 h), the muscle fiber structure obviously broke and curled, and the sarcomere structure disappeared at 150 h. After hardening (102 h), the morphology of the mitochondria changed, including swelling, cristea breaking and membrane structure disappearance. The arginine phosphate content decreased gradually from the initial 4.618 to 1.306µmol/g at 48 h, and there was no further obvious change. The ATP content decreased from 6.02 to 1.07µmol/g in 120 h. The mitochondrial membrane potential (Δφ) was measured by a fluorescence method (JC-1). The changes in freshness could be divided into three classes according to the Δφ difference between the mitochondria in the adductor muscle after adding ADP and CCCP. Mitochondrial function was complete from 0 to 6 h; mitochondrial function began to decline at 6 to 48 h; and mitochondrial function completely disappeared after 48 h. The results showed that the mitochondrial membrane potential compared with other indicators could more sensitively reflect the changes in freshness during the cold storage hardening process of the adductor muscle. PRACTICAL APPLICATION: It is very important to interprete the post-mortem energy metabolism for controlling the muscle quality of Yesso scallop. The K value which was developed based on ATP-related compounds is widely used in evaluating the freshness of seafood. Mitochondria is the main sites of cellular energy metabolism and the changes of its structure and activity can sensitively reflect the quality changes in muscle cell. It is expected to develop a more sensitive freshness evaluation index.

Acetylation inhibition alleviates energy metabolism in muscles of minipigs varying with the type of muscle fibers

In this study, we investigated whether preslaughter chemical-induced acetylation affected postmortem energy metabolism and pork quality. Thirty pigs were randomly assigned to control, acetyltransferase inhibitor (ATi) or deacetyltransferase inhibitor treatments. Serum, trapezius, longissimus lumborum, psoas major, semimembranosus and semitendinosus muscles were taken for analyses. The results indicated that ATi treatment significantly reduced the activities of lactate dehydrogenase and creatine kinase and heat shock protein 70 in serum (P < 0.05). ATi treatment increased ATP and glycogen content, but decreased lactic acid content in trapezius, psoas major and semitendinosus muscles (P < 0.05). A total of 13 acetylated proteins bands were identified and the deacetylation of creatine kinase may play a key role in slowing down the postmortem energy metabolism in ATi-treated group. In addition, ATi treatment reduced the rate of postmortem glycolysis in muscles with higher oxidative but lower glycolytic fibers. These findings provide a new insight into the underlying mechanism on muscle-specific postmortem changes of pork quality.

Insights on meat quality from combining traditional studies and proteomics

Following a century of major discoveries on the mechanisms determining meat colour and tenderness using traditional scientific methods, further research into complex and interactive factors contributing to variations in meat quality is increasingly being based on data-driven “omics” approaches such as proteomics. Using two recent meta-analyses of proteomics studies on beef colour and tenderness, this review examines how knowledge of the mechanisms and factors underlying variations in these meat qualities can be both confirmed and extended by data-driven approaches. While proteomics seems to overlook some sources of variations in beef toughness, it highlights the role of post-mortem energy metabolism in setting the conditions for development of meat colour and tenderness, and also points to the complex interplay of energy metabolism, calcium regulation and mitochondrial metabolism. In using proteomics as a future tool for explaining variations in meat quality, the need for confirmation by further hypothesis-driven experimental studies of post-hoc explanations of why certain proteins are biomarkers of beef quality in data-driven studies is emphasised.

Early Postmortem Metabolism and Protease Activation in Bovine Muscles

ObjectivesThe conversion of muscle to meat is largely controlled by postmortem energy metabolism and pH decline. These biochemical changes influence activity of enzymes implicated in proteolysis and meat tenderization. Therefore, our objective was to investigate pH decline, muscle energy metabolism, and protease activation in functionally distinct bovine muscles.Materials and MethodsSteers (n = 6) were harvested at approximately 18.5 mo and 630 kg live weight. Samples from the longissimus lumborum (LL) and diaphragm (Dia) were taken at 1, 3, and 24h postmortem, immediately frozen using liquid nitrogen, and stored in ultra-freezer until analysis. Muscle pH was obtained using a pH meter at the same time points. Myosin heavy chain composition (I, IIa, and IIx) was determined using gel electrophoresis. Substrate (residual glycogen), as well as glycolytic metabolites, glucose, glucose-6-phosphate, and lactate, were quantified by enzymatic methods; muscle ATP at 1 and 3h was also determined. Western blotting was used to evaluate protease activation (calpain-1 and caspase-3). Data were analyzed using a randomized block design, with slaughter date as block. Animal within slaughter date was considered as random effect and fixed effects of muscle, time, and the interaction tested. Time was considered a repeated measure.ResultsDiaphragm contained a greater percentage of slow myosin heavy chain compared to LL (80% vs. 12%, respectively). Consistent with fiber type, LL contained greater glycogen than Dia at 1h (P &lt; 0.05), but not at subsequent times postmortem. Overall, a greater decline in glycogen occurred in LL. Accordingly, lactate concentration increased markedly in LL postmortem and to a lesser extent in Dia (interaction effect; P &lt; 0.01). Although muscles exhibited similar lactate content at 1h, at 24h the LL showed elevated lactate relative to Dia (88 vs. 53 µmol/g tissue, respectively). Accumulation of glucose and glucose-6-phosphate were affected by muscle (P &lt; 0.01) and time (P &lt; 0.01), with greater final content in LL compared to Dia. Muscles exhibited different patterns of postmortem pH decline (muscle × time, P &lt; 0.0001). Initially, pH of LL was higher than Dia (P &lt; 0.01) and remained different at 3h (P &lt; 0.05); but by 24h, pH values were similar. Content of ATP was influenced by muscle (P &lt; 0.01) and time (P &lt; 0.01). Initial ATP was greater (P &lt; 0.01) in LL than in Dia and remained greater (P = 0.002) at 3h postmortem. From 1 to 24h, the pattern of calpain autolysis differed between muscles (interaction effect; P = 0.01). Calpain-1 autolysis was similar at all times in Dia, whereas autolysis increased in LL from 3h to 24h postmortem. Caspase-3 was identified by one band (32 kDa) that represents the zymogen (procaspase-3). Procaspase-3 content is affected by muscle (P &lt; 0.01), with Dia containing greater content than LL.ConclusionAlthough the Dia is considered a slow muscle, it exhibited a more rapid pH decline and lower ATP levels than LL early postmortem. These parameters were expected to coincide with more rapid calpain-1 autolysis in Dia, but this was not the case. Further work is necessary to understand the interaction between pH decline, muscle type, and postmortem proteolysis.

Muscle Energy Metabolism, Growth, and Meat Quality in Beef Cattle

World meat production must increase substantially to support current projections in population growth over the next 30 years. However, maximizing product quality remains a focus for many in the meat industry, as incremental increases in product quality often signal potential increases in segment profitability. Moreover, increases in meat quality also address concerns raised by an ever-growing affluent society demanding greater eating satisfaction. Production strategies and valued endpoints differ worldwide, though this makes the global marketing of meat challenging. Moreover, this variation in production schemes makes it difficult for the scientific community to understand precisely those mechanisms controlling beef quality. For example, some cattle are produced in low input, extensive, forage-based systems. In contrast, some producers raise cattle in more intensive operations where feeding programs are strategically designed to maximal growth rates and achieve significant fat deposition. Yet, others produce cattle that perform between these two extremes. Fresh meat quality, somewhat like the variation observed in production strategies, is perceived differently across the globe. Even so, meat quality is largely predicated on those characteristics visible at the retail counter, namely color and perceived texture and firmness. Once purchased, however, the eating experience is a function of flavor and tenderness. In this review, we attempt to identify a few areas where animal growth may impact postmortem energy metabolism and thereby alter meat quality. Understanding how animals grow and how this affects meat quality development is incumbent to all vested in the meat industry.

Identification of meat quality-related differentially methylated regions in the DNA of the longissimus dorsi muscle in pig

The objective of this study was to investigate the association of DNA methylation with postmortem energy metabolism and the pH of the porcine longissimus dorsi muscle (LDM). Analysis of the DNA methylome of eight LDM samples (four pairs of the highest and lowest pH among littermates) identified a total of 3468 differentially methylated regions (DMRs) between high and low pH samples (p ≤ 0.001). Of DMRs, 45.3% co-mapped with quantitative trait loci known to be associated with meat pH and postmortem metabolism. Among the DMRs, 203 hyper-methylated regions (HR) and 190 hypo-methylated regions (HO) were identified for the high pH group compared to the low pH. Furthermore, 44 and 21 protein-coding genes contained HR and HO in their gene body, respectively. It was revealed that ENO1, GYS2, SDHC and DERA, which encode core enzymes in postmortem energy metabolism, contained HR or HO in their gene body.

Early Postmortem Metabolism and Protease Activation in Bovine Muscles

ObjectivesThe conversion of muscle to meat is largely controlled by postmortem energy metabolism and pH decline. These biochemical changes influence activity of enzymes implicated in proteolysis and meat tenderization. Therefore, our objective was to investigate pH decline, muscle energy metabolism, and protease activation in functionally distinct bovine muscles.Materials and MethodsSteers (n = 6) were harvested at approximately 18.5 mo and 630 kg live weight. Samples from the longissimus lumborum (LL) and diaphragm (Dia) were taken at 1, 3, and 24h postmortem, immediately frozen using liquid nitrogen, and stored in ultra-freezer until analysis. Muscle pH was obtained using a pH meter at the same time points. Myosin heavy chain composition (I, IIa, and IIx) was determined using gel electrophoresis. Substrate (residual glycogen), as well as glycolytic metabolites, glucose, glucose-6-phosphate, and lactate, were quantified by enzymatic methods; muscle ATP at 1 and 3h was also determined. Western blotting was used to evaluate protease activation (calpain-1 and caspase-3). Data were analyzed using a randomized block design, with slaughter date as block. Animal within slaughter date was considered as random effect and fixed effects of muscle, time, and the interaction tested. Time was considered a repeated measure.ResultsDiaphragm contained a greater percentage of slow myosin heavy chain compared to LL (80% vs. 12%, respectively). Consistent with fiber type, LL contained greater glycogen than Dia at 1h (P < 0.05), but not at subsequent times postmortem. Overall, a greater decline in glycogen occurred in LL. Accordingly, lactate concentration increased markedly in LL postmortem and to a lesser extent in Dia (interaction effect; P < 0.01). Although muscles exhibited similar lactate content at 1h, at 24h the LL showed elevated lactate relative to Dia (88 vs. 53 µmol/g tissue, respectively). Accumulation of glucose and glucose-6-phosphate were affected by muscle (P < 0.01) and time (P < 0.01), with greater final content in LL compared to Dia. Muscles exhibited different patterns of postmortem pH decline (muscle × time, P < 0.0001). Initially, pH of LL was higher than Dia (P < 0.01) and remained different at 3h (P < 0.05); but by 24h, pH values were similar. Content of ATP was influenced by muscle (P < 0.01) and time (P < 0.01). Initial ATP was greater (P < 0.01) in LL than in Dia and remained greater (P = 0.002) at 3h postmortem. From 1 to 24h, the pattern of calpain autolysis differed between muscles (interaction effect; P = 0.01). Calpain-1 autolysis was similar at all times in Dia, whereas autolysis increased in LL from 3h to 24h postmortem. Caspase-3 was identified by one band (32 kDa) that represents the zymogen (procaspase-3). Procaspase-3 content is affected by muscle (P < 0.01), with Dia containing greater content than LL.ConclusionAlthough the Dia is considered a slow muscle, it exhibited a more rapid pH decline and lower ATP levels than LL early postmortem. These parameters were expected to coincide with more rapid calpain-1 autolysis in Dia, but this was not the case. Further work is necessary to understand the interaction between pH decline, muscle type, and postmortem proteolysis.

Presence of oxygen and mitochondria in skeletal muscle early postmortem

Anaerobic glycolysis dominates energy metabolism postmortem. Even so, however, recent studies suggest mitochondria can modify postmortem energy metabolism and may contribute to pH decline, possibly affecting the transformation of muscle to meat and fresh meat quality development. Because oxygen is a necessary component of mitochondrial function, oxygenation of porcine and bovine longissimus thoracis et lumborum was determined postmortem using NIR spectroscopy. The ratio of oxy- to deoxymyoglobin decreased with time postmortem in both species. Metabolic analyses of muscle samples collected over the same timeframe also revealed fluctuations in TCA intermediates. Finally, mitochondria collected from muscle of electrically stimulated carcasses differed from those of non-stimulated muscle. Collectively, these data support the thesis that muscle mitochondria function early postmortem and may play a more active part in pH decline and possibly meat quality development.

Wnt gene expression in adult porcine longissimus dorsi and its association with muscle fiber type, energy metabolism, and meat quality

This study investigated the expression profiles of Wnt genes in adult porcine longissimus dorsi (LD) from different porcine genotypes and their associations with meat quality. The results showed that Wnt5a gene expression level was the highest in Jinhua (JHP) pigs, followed by Zhongbai (ZBP), Duroc×Zhongbai (DZB), and Duroc×Yorkshire×Landrace (DYL) pigs, with significant differences between ZBP, DZB, and DYL (P<0.05). This genotypic order was reversed for Wnt7a, Wnt10b, and Wnt11 expression, with JHP and DYL having the lowest and highest expressive levels, respectively. Wnt5a expression was negatively correlated with pH45 min and ΔpH (P<0.01), some glycolytic markers (P<0.05), and positively correlated with meat color (a*), shear force (SF) value (P<0.05), myosion heavy chain (MyHC) I mRNA proportion (P<0.01), turnover ratio of creatine phosphate (CP), and creatine kinase (CK) activity (P<0.05). Opposite correlations were observed for Wnt2, Wnt7a, Wnt10b, and Wnt11. These results revealed that Wnt5a, Wnt7a, Wnt10b, and Wnt11 gene expressions in adult porcine muscle contributed to differences between porcine genotypes and affected pork quality. Wnt5a gene expression could be beneficial for the formation of high quality pork by regulating muscle fiber types and postmortem energy metabolism.

Different Statistical Approaches to Investigate Porcine Muscle Metabolome Profiles to Highlight New Biomarkers for Pork Quality Assessment.

The aim of this study was to elucidate the underlying biochemical processes to identify potential key molecules of meat quality traits drip loss, pH of meat 1 h post-mortem (pH1), pH in meat 24 h post-mortem (pH24) and meat color. An untargeted metabolomics approach detected the profiles of 393 annotated and 1,600 unknown metabolites in 97 Duroc × Pietrain pigs. Despite obvious differences regarding the statistical approaches, the four applied methods, namely correlation analysis, principal component analysis, weighted network analysis (WNA) and random forest regression (RFR), revealed mainly concordant results. Our findings lead to the conclusion that meat quality traits pH1, pH24 and color are strongly influenced by processes of post-mortem energy metabolism like glycolysis and pentose phosphate pathway, whereas drip loss is significantly associated with metabolites of lipid metabolism. In case of drip loss, RFR was the most suitable method to identify reliable biomarkers and to predict the phenotype based on metabolites. On the other hand, WNA provides the best parameters to investigate the metabolite interactions and to clarify the complex molecular background of meat quality traits. In summary, it was possible to attain findings on the interaction of meat quality traits and their underlying biochemical processes. The detected key metabolites might be better indicators of meat quality especially of drip loss than the measured phenotype itself and potentially might be used as bio indicators.

Skeletal muscle transcriptional profiles in two Italian beef breeds, Chianina and Maremmana, reveal breed specific variation.

Chianina and Maremmana breeds play an important role in the Italian cattle meat market. The Chianina breed is an ancient breed principally raised for draught. Now this breed is the worldwide recognized producer of top quality beef, tasteful and tender, specifically the famous "Florentine steak". The Maremmana characterized by a massive skeletal structure, is a rustic cattle breed selected for adaptability to the marshy land of the Maremma region. We used a high throughput mRNA sequencing to analyze gene expression in muscle tissues of two Italian cattle breeds, Maremmana (MM) and Chianina (CN) with different selection history. We aim to examine the specific genetic contribution of each breed to meat production and quality, comparing the skeletal muscle tissue from Maremmana and Chianina. Most of the differentially expressed genes were grouped in the Glycolysis/Gluconeogenesis pathways. The rate and the extent of post-mortem energy metabolism have a critical effect on the conversion of muscle to meat. Furthermore, we aim at discovering the differences in nucleotide variation between the two breeds which might be attributable to the different history of selection/divergence. In this work we could emphasize the involvement of pathways of post-mortem energy metabolism. Moreover, we detected a collection of coding SNPs which could offer new genomic resources to improve phenotypic selection in livestock breeding program.

Skeletal muscle proteome and meat quality of broiler chickens subjected to gas stunning prior slaughter or slaughtered without stunning

ABSTRACTThe study examined the effects of pre-slaughter gas stunning and slaughter without stunning on meat quality and skeletal muscle proteome of broiler chickens. Fifty Cobb broiler chickens were randomly assigned to either a neck cut without pre-slaughter stunning (Halal slaughter) or pre-slaughter gas stunning followed by a neck cut. Samples of Pectoralis major muscle at 7 min, 4 h and 24 h postmortem were analyzed for pH, shear force, color, drip and cooking losses. Proteome profile of the 7 min samples was examined by two-dimensional polyacrylamide gel electrophoresis. Birds subjected to Halal slaughter had higher (P < 0.05) redness than those gas stunned at 4 and 24 h postmortem. Gas-stunned birds had lower (P < 0.05) muscle pH and shear force and higher (P < 0.05) drip and cooking losses compared with those subjected to Halal slaughter throughout postmortem storage. Gas stunning up-regulated (P < 0.05) the expression of beta-enolase, pyruvate kinase and creatine kinase compared with Halal slaughter. Results indicate that pre-slaughter gas stunning hastened postmortem energy metabolism and had detrimental effects on the water holding capacity and redness of broiler breast muscles.

Effect of creatine monohydrate supplementation on carcass traits, meat quality and postmortem energy metabolism of finishing pigs

The objective of this study was to evaluate the effects of creatine monohydrate (CMH) supplementation on meat quality and postmortem energy metabolism of finishing pigs. In total, 48 healthy Duroc–Large White cross castrated male pigs were randomly allocated into two treatments, and fed either a CHM-free basal diet or a basal diet with CMH supplementation (0.8%) for 14 days. At the end of the experiment, six pigs from each treatment were weighed individually and slaughtered. The muscle from longissimus dorsi was collected to evaluate the meat quality and energy metabolism-related parameters. The results showed that CMH supplementation did not affect the loin eye area, back fat depth or dressing percentage (P &gt; 0.05). The muscle pH45 min was higher, whereas drip loss and cooking loss were lower in the CMH supplementation group (P &lt; 0.05). CMH supplementation increased the concentrations of creatine (P &lt; 0.05), adenosine triphosphate (P &lt; 0.05), adenosine diphosphate (P &lt; 0.01) and creatine kinase activity (P &lt; 0.05), and decreased the concentration of lactic acid (P &lt; 0.05), and the activities of lactate dehydrogenase (P &lt; 0.05) and pyruvate kinase (P &lt; 0.05) in muscle postmortem. However, no differences were observed between groups for chemical composition, textural characteristics and glycolytic potential of longissimus dorsi muscle (P &gt; 0.05). These findings suggest that dietary supplementation with CMH during the finishing period in pigs could delay early pH decline and decrease the rate of glycolysis in postmortem longissimus dorsi muscle resulting in a decreased drip loss.

Altered AMP deaminase activity may extend postmortem glycolysis

Postmortem energy metabolism drives hydrogen accumulation in muscle and results in a fairly constant ultimate pH. Extended glycolysis results in adverse pork quality and may be possible with greater adenonucleotide availability postmortem. We hypothesized that slowing adenonucleotide removal by reducing AMP deaminase activity would extend glycolysis and lower the ultimate pH of muscle. Longissimus muscle samples were incorporated into an in vitro system that mimics postmortem glycolysis with or without pentostatin, an AMP deaminase inhibitor. Pentostatin lowered ultimate pH and increased lactate and glucose 6-phosphate with time. Based on these results and that AMPK γ3R200Q mutated pigs (RN−) produce low ultimate pH pork, we hypothesized AMP deaminase abundance and activity would be lower in RN− muscle than wild-type. RN− muscle contained lower AMP deaminase abundance and activity. These data show that altering adenonucleotide availability postmortem can extend postmortem pH decline and suggest that AMP deaminase activity may, in part, contribute to the low ultimate pH observed in RN− pork.

Comparison of the meat quality, post-mortem muscle energy metabolism, and the expression of glycogen synthesis-related genes in three pig crossbreeds

Post-mortem muscle energy metabolism plays an important role in pork quality. To analyse the differences of meat quality and energy metabolism, three commercial pig crossbreeds frequently used in China were studied, they were DT (Duroc × Taihu; n = 16), PIC (five-way crossbreed from Pig Improvement Co., UK; n = 29) and DLY (Duroc × (Landrace × Yorkshire); n = 19) pigs. The results showed that DT pigs had a higher post-mortem pH45 min and pH24 h, lower shear force and drip loss, higher muscle free-glucose and glycogen contents, and lower lactic acid content than did PIC and DLY pigs. Post-mortem muscle free-glucose content of these three pig crossbreeds changed little, from 45 min to 96 h post-mortem. The expression levels of PRKAG3 (encoding a regulatory subunit of the AMP-activated protein kinase) and GYS1 (encoding muscle glycogen synthase) genes of DT pigs were significantly lower than those of PIC and DLY pigs. DT pigs had a higher expression level of glycogenin-1-like (encoding glycogenin) gene than did PIC and DLY pigs. In conclusion, DT pigs had better meat quality than did the other two pig crossbreeds. We deduced that the post-mortem muscle energy status and metabolism of DT pigs might be an important reason for their good meat quality, and future research should focus on the molecular and physiological mechanism of post-mortem muscle energy metabolism to find ways to improve meat quality.